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No. 748,978. PATBNTBD JAN. 5, 1904.

' P. DE NCRDBNFBLT C E. TERNSTRCM. BCCENTRIC SCREW BRBECH CLCSINC DEVICE.

APPLIOATION FILED SEPT. 12, 1903.

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No. 748,978. PATENTED JAN.5,19C4.

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ECCENTEIC SCREW EEEECE CLCsINC DEVICE.

APPLIOATION FILED SEPT. 12, 1903.

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UNTTED STATES Patented January 5, 1904.

ATENT @Prion ECCENTRIC-SCREW BREECH-CLOSING DEVICE.

SPECIFICATION forming part of Letters Patent No. 748,978, dated January 5, 1904.

Application iiled September 12, 1903. Serial No. 172,897. (No model.)

T0 @ZZ whont it may Concern.:

Be it known that we, PER DE NORDENFELT and ERNST TERNSTRM, engineers, subjects of the King of Sweden and Norway, residing at 8 Rue Auber, Paris, in the Republic of France, have invented certain new and useful Improvements in Eccentric-Screw Breech- Closing Devices, of which the following is a specification.

This invention relates to an arrangement for facilitating the operation of the eccentric screw, particularly in heavy ordnance. Endeavors have already been made to facilitate such operation by means of bearing-balls on which the screw turns with less friction. However, this means is only an insuflcient palliative in the case of heavy ordnance, because it does not diminish the variable resistance arising from the eccentric position of the center of gravity of the screw relatively l to the axis around which it rotates.

The present invention has for its purpose to com-pensate the detrimental eiect due to the displacement of the center of gravity; and it consists in principle in arranging a resilient system taking support on the breech and acting on the screw in sucha manner as to counterbalance its weight as much as possible. This compensating system is preferably used conjointly with some suitable means for diminishing the coefficient of the As a resilient system we use, preferably, a spring, one end of which is connected to the breech and the other end of which acts either directly or through the medium of rods or levers and in an upward direction on a trunnion integral with the screw and suitably located relatively to the center of gravity of the said screw. As the weight of the screw itself is constant during the rotation, it is convenient to render as constant as possible the eort intended to compensate the said Weight, and for that purpose it is advantageous to interpose between the spring and the Screw a lever or other equivalent device by means of which the power of the spring, which varies as it expands or contracts, is transmitted to the screw by an increased or decreased leverage, the difference varying inversely to the said power.

In the accompanying drawings we show by Ihaving an outer spring.

way of example and dagrammatically several forms of our invention.

Figures 1 and 2 are respectively a longitudinal and a transversal section of an eccentric-screw breech having an inner spring. Figs. 3 and 4 are respectively a longitudinal section and an end elevation ofanother breech Figs. 5 and 6 are respectively a longitudinal and a transversal section of a breech having an outer spring and an equalizing-lever.

In the figures the threads ofthe screw, the operating devices, and other parts are not shown, as not being of any interest in that which concerns this invention.

In Figs. l and 2, ct designates the breech, and b the screw, with its housing c for the projectile. d is the axis of rotation of the screw. In a mortise f in the form of a segment is fixed a trunnion g, located in the eenter of gravity G of the screw, and on the said trunnion is jointed the upper end of a vertical spiral spring h, which at the bottom rests in a box t, fixed to the breech. the screw is turned to bring its housing c in front of the bore of the cannon, the center of gravity-that is to say, the trunnion g-describes an arc g g', and the spring t is compressed. On the other hand, when the screw is brought back into its initial and closing position the spring is expanded. In both these movements the action of the spring is always directed,according to the center of gravity, upwardly and nearly vertically. As the power of the spring is so regulated as to be as much as possible equal to the weight of the screw, it will be understood that the said screw is nearly exactly counterbalanced in all its positions and that the resistances opposed to its movement are almost entirely suppressed. However, there still remains a certain want of equipoise on account of the variation in the power of the spring when the latter is expanded or contracted, so that during a part of the oscillation of the screw the latter can bear downward in the breech and bear upward during another part. The friction resulting from this want of equipoise can be reduced either in arranging one or more rolls u around the screw, as shown in Figs. 7 and 8, or in mounting the screw on two central pivots la and o, as shown in Figs. 9 and When i 10, or even on a single central pivot, as shown in Figs. 3 and 4. In that case the trunnion g is preferably located on the outer face of the screw a at a point situated in a straight line with the center of gravity G of the screw and with the central pivot lc arranged in the inner face of the said screw. The spring h is also located at the outside in a box z', mounted on a pivotj on the breech, the said box being connected to the trunnion g by a piston fm. The pivot la then supports about the half of the weight of the screw, and the spring has a power of nearly counterbalancing the other half of the weight. It is still advantageous to arrange one or more rollers around the screw in order to obviate the variations in the power of the spring which still exist, although Very much reduced, and which causes the screw to bear sometimes upward and sometimes downward in the breech.

The above-mentioned want of equipoise can even be completely nullifled by the use of an equalizing device intermediate the spring and the screw-as, for instance, a bent lever n, fulcrumed at on the breech, Figs. 5 and 6. The said lever acts by means of a roller p on the under side of a portion of greater diameter ot the trunnion g, formed concentrically to the center of gravity G in a mortisefin the screw. The spring h, held against a fixed part q and connected to the levern byarod r, acts on the latter with a force which is all the greater, but with a lever-arm all the weaker, as it is more compressed, so that the momentum of this force or power relatively to the pivot 0 is preceptibly constant. Consequently the pressure of the rollerp on the under side of the trunnion g, exercised in the direction of the line between the centers p G, is also preceptibly constant. Therefore this invention permits of rendering the screw floating, as it were, in the breech and quite free to turn in all positions.

A great number of arrangements may of course be used for the springs and for the intermediate devices which connect them to the screw, according to whether the said springs are of coiled, flat, spiral, washer, or other form. In Figs. 7 and 8, for instance, the spring h is made up of juxtaposed springplates and is jointed at its ends at G to the trunnion g and at fw to the breech, the pivots g and w being perceptibly on the same vertical line.

In Figs. 9 and 10 the elastic system comprises a rigid lever m, jointed to the trunnion g, a spring-barrelg/,jointed to the pivotw, and a spiral spring z, connecting the lever 0c with the spring-barrel, so that the said system tends to open out as does the spring h in Fig. 8, and thus to move the trunnion g vertically upward.

We may also combine with the screw two or more elastic systems, the downward and upward actions of which on the screw havea resultant passing through the center of gravity or as nearly so as possible. For instance, there may be located at s and t, Fig. 5, two systems such as that shown in that igure.

We claim- 1. In an eccentric screw for closing the breech of guns, the combination, with the screw and breech, of an elastic system connected to the breech and to the screw to counterbalance the weight of the said screw.

2. In an eccentric screw forclosing breeches, the combination, with the screw and breech, of aspring connected to the breech and which lifts the screw vertically upward.

3. In an eccentric screw for closing the breech of guns, the combination, with the screw and breech, of a spring connected to the breech, of a trunnion on the screw, and

of means for transmitting the power of theY spring to the trunnion in a vertical direction.

4. In an eccentric screw for closing breeches, the combination, with the screw and breech, of a spring connected to the breech, of a transversal mortise in the screw, of a trunnion formed in the said mortise coneentrically to the center of gravity of the eccentric screw, and of means for transmitting the power of the spring to the trunnion in a vertical direction.

5. In an eccentric screw for closing the breech of guns, the combination, with the screw and breech, of a spring connected to the breech, of a trunnion formed in the screw concentrically to the center of gravity of the latter, of means fortransmitting the power of the spring to the said trunnion in a vertical direction, and of pivots of support for the screw arranged in line with the axis of rotation of the screw.

6. In an eccentric screw for closing the breech of guns, the combination, with the screw and breech, of a spring connected to the breech,of aleverfulcru med on the breech, of a roller on the said lever, of a transversal mortise in the screw, of a trunnion formed in the said mortise concentrically to the center of gravity of the screw, the said rolleracting on the under side of the said trunnion, and the said spring being located, relatively to the fulcrum of the lever, in such a manner that it acts on the said lever with a leverage which becomes all the weaker as the spring is more compressed, as hereinbefore specified.

In testimony that we claim the foregoing as our invention we have signed our names in presence of two subscribing witnesses.

PER DE NORDENFELT. ERNST TERNSTROM. Witnesses:

PAUL F. PQET, MAURICE Roux.

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